The invention relates to a suspension assembly for a vehicle, for suspending a second vehicle mass, such as a cabin or wheels, to a first vehicle mass, such as a chassis. More particularly, the invention relates to an active suspension assembly, arranged to actively counterbalance external loads acting on said suspended vehicle mass.
Such a suspension assembly is for instance known from WO 93/22150 and WO 2006/019298. The known assembly comprises a bearing arm, which at one end is pivotally connected to a chassis of the vehicle and at another end is associated to a cabin or wheel. Spring means are provided to produce a spring force that can exert a moment on the bearing arm, in order to counteract an external moment acting on said bearing arm due to for instance lateral, longitudinal and/or vertical accelerations of the vehicle (roll, pitch and heave respectively). Adjustment means are provided to alter a direction and/or the point of application of the spring force, so as to decrease or increase the counter moment on the bearing arm.
A disadvantage of this known suspension assembly is that the effective spring stiffness of the suspension assembly depends to a large extent on the instantaneous position of the point of application of the spring force. When this point of application is located near the pivot axis, the effective spring stiffness may generally be low, while it may be relatively high while the point of application is located near the opposite end of the bearing arm. Both situations may result in undesirable and/or uncomfortable drive behaviour.
It is therefore an objective of the invention to provide a suspension assembly of the above-described type, in which the disadvantage of the known assembly is overcome or at least reduced, while retaining the advantages thereof.
To this end a suspension according to the present invention is characterized by the features of claim 1.